DE102013203603A1 - Exhaust gas treatment system with a solid, ammonia gas generating material - Google Patents

Abstract

An exhaust treatment system for an internal combustion engine is provided that includes an exhaust line, a pressurized vessel, a selective catalytic reduction ("SCR") device, and a control module. The internal combustion engine has a plurality of pistons and an engine off condition indicating that the pistons are generally stationary. The exhaust conduit is in fluid communication with the internal combustion engine and is configured to receive exhaust gas from the internal combustion engine. The pressurized vessel stores a solid ammonia gas generating material. The pressurized vessel is selectively activated to heat the solid ammonia gas generating material into an ammonia gas. The ammonia gas is released into the exhaust pipe. The SCR device is in fluid communication with the exhaust line and is configured to receive the ammonia gas.

Description

FIELD OF THE INVENTION

Exemplary embodiments of the invention relate to exhaust treatment systems for internal combustion engines, and more particularly to an exhaust treatment system having a pressurized vessel that is selectively activated to heat a solid ammonia gas producing material into an ammonia gas.

BACKGROUND

The exhaust gas expelled from an internal combustion engine, particularly a diesel engine, is a heterogeneous mixture containing gaseous emissions such as carbon monoxide ("CO"), unburned hydrocarbons ("HC"), and nitrogen oxides ("NO _x ") also contains condensed phase materials (liquids and solids) that form particulate matter ("PM"). Catalyst compositions, typically disposed on catalyst carriers or substrates, are provided in an engine exhaust system to convert some or all of these exhaust constituents to unregulated exhaust gas components.

One type of exhaust treatment technology for reducing CO and HC emissions is an oxidation catalyst device ("OC"). The OC device comprises a flow-through substrate and a catalyst compound applied to the substrate. One type of exhaust treatment technology for reducing NO _x emissions is a selective catalytic reduction ("SCR") device that may be positioned downstream of the OC device. The SCR device includes a substrate having an SCR catalyst compound applied to the substrate.

In one approach, a reductant is typically sprayed into hot exhaust gases upstream of the SCR device. The reducing agent may be an aqueous urea solution which decomposes into ammonia ("NH ₃ ") in the hot exhaust gases and is adsorbed by the SCR device. The ammonia then reduces the NO _x to nitrogen in the presence of the SCR catalyst. However, the SCR device must reach a threshold or light-off temperature to reduce _NOx effectively. During a cold start of the engine, the SCR device has not reached the respective light-off temperature and therefore can not generally remove effectively NO _x from the exhaust gases.

There may be several disadvantages when spraying an aqueous urea solution into the exhaust gas. For example, the tanks that store the aqueous urea solution can be heavy and bulky and therefore contribute to the weight and cost of a vehicle. Also, during certain operating conditions, such as low ambient temperatures, the aqueous urea solution can freeze (ie, below the freezing temperature of the urea solution, which is usually about minus 12 ° C). As a result, the urea solution loses its ability to inject into the exhaust stream through an injector. Thus, to maintain the effectiveness of the injector, the provision of electrical heating may be required to thaw the urea solution, which also adds to the weight and cost of a vehicle. Accordingly, it is desirable to provide an efficient, cost effective approach for effectively removing NO _x from the exhaust gas.

SUMMARY OF THE INVENTION

In an exemplary embodiment of the invention, an exhaust treatment system for an internal combustion engine is provided that includes an exhaust conduit, a pressurized vessel, a selective catalytic reduction ("SCR") device, and a control module. The internal combustion engine has a plurality of pistons and an engine-off condition indicating that the pistons are generally stationary. The exhaust conduit is in fluid communication with the internal combustion engine and is configured to receive an exhaust gas from the internal combustion engine during operation. The pressurized vessel stores a solid, ammonia gas generating material. The pressurized vessel is selectively activated to heat the solid ammonia gas generating material into an ammonia gas. The ammonia gas is released into the exhaust pipe. The SCR device is in fluid communication with the exhaust conduit and is configured to receive the ammonia gas. The SCR device has an SCR temperature profile and an SCR light-off temperature. The control module is in communication with the engine and the pressurized vessel. The control module receives a signal indicative of the engine off condition. The control module has a memory for storing a value indicative of a target amount of the ammonia gas released into the exhaust passage through the pressurized vessel and charged to the SCR device. The control module includes control logic for determining whether the engine is in the engine-off state based on the signal. The control module has control logic for determining the SCR temperature profile. The control module includes control logic for determining if the SCR temperature profile is below a threshold when the engine is in the engine-off state. The threshold indicates that the SCR Device is a specified size below the SCR light-off temperature. The control module includes control logic for determining if the pressurized vessel has released the target amount of ammonia gas into the exhaust passage when the SCR temperature profile is below the threshold. The control module has control logic for deactivating the pressurized vessel if the pressurized vessel has released the target amount of ammonia gas.

The above features and advantages and other features and advantages of the invention will be readily apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features, advantages and details will become apparent in the following detailed description of embodiments only by way of example, the detailed description of which refers to the drawings, in which:

1 FIG. 3 is a schematic diagram of an exemplary exhaust treatment system; FIG. and

2 Fig. 10 is a process flow diagram showing a method of activating a pressurized vessel to heat a solid ammonia gas generating material into an ammonia gas.

DESCRIPTION OF THE EMBODIMENTS

The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. The term module as used herein refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated or group) and memory that executes one or more software or firmware programs, a combinational logic circuit and / or other suitable components that provide the described functionality.

With reference now to 1 is an exemplary embodiment of an exhaust treatment system 10 for the reduction of regulated exhaust components of a combustion ("IC") engine 12 directed. The exhaust treatment system described herein may be implemented in various engine systems that may include, but are not limited to, diesel engine systems, gasoline engine systems, and homogeneous compression ignition engine systems. In the example, as shown, the engine is pointing 12 a plurality of pistons 16 on. For example, the engine 12 be an eight-cylinder or a twelve-cylinder engine, but it should be understood that just as any number of pistons 16 can be used.

The exhaust treatment system 10 generally has one or more exhaust pipes 14 and one or more exhaust treatment devices. In the embodiment, as shown, the exhaust treatment system devices include a hydrocarbon adsorber 20 , a device 22 with electrically heated catalyst ("EHC"), an oxidation catalyst device ("OC") 24 , a Selective Catalytic Reduction Device ("SCR") 26 and a particulate filter device ("PF") 30 on. As noted, the exhaust treatment system of the present disclosure may include various combinations of one or more of those described in U.S. Pat 1 shown exhaust treatment devices and / or other exhaust treatment devices (not shown) and is not limited to the present example.

In 1 transports the exhaust pipe 14 , which may include multiple segments, exhaust 15 from the internal combustion engine 12 to the various exhaust treatment devices of the exhaust treatment system 10 , The hydrocarbon adsorber 20 includes z. A through-flow metal or ceramic monolith substrate. The substrate may have a hydrocarbon adsorber compound disposed thereon. The hydrocarbon adsorbent compound may be applied as a washcoat and may include materials such as zeolite. The hydrocarbon adsorber 20 is upstream of the EHC device 22 , the OC device 24 and the SCR device 26 arranged. The hydrocarbon adsorber 20 is configured to reduce the emissions of HC during an engine cold-start condition when the EHC device 22 , the OC device 24 and the SCR device 26 have not been heated to the respective light-off temperatures and are not active by acting as a mechanism for storing exhaust emission components. Specifically, the zeolite-based material is used to store fuel or hydrocarbons during a cold start.

The OC device 24 is downstream of the hydrocarbon adsorber 20 and may, for example, comprise a flow-through metal or ceramic monolith substrate placed in a stainless steel bowl or canister having an inlet and an outlet in fluid communication with the exhaust conduit 14 can be packed. The substrate may have an oxidation catalyst compound disposed thereon. The Oxidation catalyst compound may be applied as a washcoat and may include metals such as platinum ("Pt"), palladium ("Pd"), perovskite or other suitable oxidizing catalysts, or a combination thereof. The OC device 24 treats unburned gaseous and non-volatile HC and CO that are oxidized to produce carbon dioxide and water.

In the embodiment, as shown, the EHC device is 22 in the OC device 24 arranged. The EHC device 22 has a monolith 28 and an electric heater 32 on, with the electric heater 32 is selectively activated and the monolith 28 heated. The electric heater 32 is connected to an electrical source (not shown) which provides power thereto. In one embodiment, the electric heater operates 32 at a voltage of about 12-24 volts and a power range of about 1-3 kilowatts, but it should be understood that other operating conditions can be used as well. The EHC device 22 may be constructed of any suitable material that is electrically conductive, such as a wound or stacked metal monolith 28 , An oxidation catalyst compound (not shown) may be applied to the EHC device 22 may be applied as a washcoat and may include metals such as Pt or Pd, perovskite or other suitable oxidizing catalysts, and combinations thereof.

The SCR device 26 may be downstream of the OC device 24 be arranged. In a way similar to the OC device 24 can the SCR device 26 For example, a through-flow ceramic or metal monolith substrate may be incorporated into a stainless steel bowl or canister having an inlet and an outlet in fluid communication with the exhaust conduit 14 can be packed. The substrate may have an SCR catalyst composition applied thereto. The SCR catalyst composition may comprise a zeolite as well as one or more base metal components, such as iron ("Fe"), cobalt ("Co"), copper ("Cu"), or vanadium ("V"), which can efficiently serve NO _x components in the exhaust gas 15 in the presence of a reducing agent, such as ammonia ("NH3").

In the example, as in 1 is shown is a pressurized vessel 40 for storing a solid ammonia gas generating material 42 intended. In one embodiment, the solid, ammonia gas generating material 42 Ammonium carbamate or ammonium carbonate. The pressurized vessel 40 is selectively activated to the solid ammonia gas generating material 42 to heat in an ammonia gas, which is in the exhaust pipe 14 injected or released. In the exemplary embodiment, as in FIG 1 is shown, the pressurized vessel 40 a plurality of heaters 44 on that along the side walls 46 of the pressurized vessel 40 are arranged. In one example, the heaters 44 Resistance elements with 200 W, which serve as heaters. The pressurized vessel 40 also has a flash or flash heater (from English: "flash heater") 48 on, on the solid, ammonia gas generating material 42 rests. A room 50 is in the pressure vessel 40 between the pressure vessel 40 and the solid gas generating material 42 intended. In one embodiment, the heaters 44 activated to the solid gas generating material 42 to heat to a temperature in the range of about 60 ° C to about 100 ° C. Subsequently, the flash heating 48 be activated to the solid gas generating material 42 to a relatively high temperature (ie, in one embodiment to about 110 ° C) to heat. The activation of the flash heater 48 generated temperature causes decomposition of the solid gas generating material 42 at the interface between the solid gas generating material 42 and the flash heating 48 , Specifically, the activation of the flash heater converts 48 the solid gas generating material 42 into ammonia gas and carbon dioxide ("CO ₂ "). The mixture of ammonia gas and carbon dioxide is passed through a tube 52 supplied with the exhaust pipe 14 connected is. The mixture of ammonia gas and the carbon dioxide is then introduced into the exhaust pipe 14 dosed or released. More specifically, the ammonia gas and the carbon dioxide become the exhaust gas line 14 released and to the SCR device 26 guided.

The pressure vessel 40 also has a pressure transducer 54 on that is used to the pressure of the room 50 to monitor in the pressure vessel 40 is placed. More precisely, the room reaches 50 finally, a threshold pressure when the solid gas generating material 42 decomposed into the ammonia gas. The threshold pressure indicates that the solid gas generating material 42 into the ammonia gas and carbon dioxide has been converted at a rate that results in a steady supply of ammonia gas coming from the SCR device 26 is required. This means the pressure vessel 40 has a normally closed solenoid valve 56 opened in the case when the pressure transducer 52 detects that the pressure in the room 50 has exceeded the threshold pressure. The opening of the solenoid valve 56 allows entry of the ammonia gas and the carbon dioxide into the exhaust pipe 14 , Thus, the threshold pressure produces the dispersion or gas spread required to deliver a target amount of ammonia gas into the exhaust conduit 14 is released to generate, which to the SCR device 26 is loaded. Specifically, in one example, the target amount of ammonia gas may represent a saturation amount of ammonia gas discharged from the SCR device 26 saved is. The saturation amount represents a maximum amount of ammonia gas that is the SCR device 26 However, it should be understood that the target amount of ammonia gas may have other sizes as well.

The PF device 30 may be downstream of the SCR device 26 be arranged. The PF device 30 serves to the exhaust 15 from carbon and other particles. In various embodiments, the PF device 30 using a ceramic wall flow monolith filter 23 may be constructed, which may be packed in a shell or a canister, which is constructed for example of stainless steel and the / an inlet and an outlet in fluid communication with the exhaust pipe 14 has. The ceramic wall flow monolith filter 23 may have a plurality of longitudinally extending passages defined by longitudinally extending walls. The passages include a subset of inlet passages having an open inlet end and a closed outlet end, and a subset of outlet passages having a closed inlet end and an open outlet end. exhaust 15 that in the filter 23 entering through the inlet ends of the inlet passages is forced through adjacent, longitudinally extending walls to the outlet passages. By this wall flow mechanism, the exhaust gas 15 filtered by carbon and other particles. The filtered particles are deposited on the longitudinally extending walls of the intake passages and over time have the effect of increasing the exhaust back pressure that the engine 12 is exposed. It should be noted that the ceramic wall flow monolith filter is merely exemplary in nature and that the PF device 30 may have other filtering devices, such as wound or packed fiber filters, open-celled foams, sintered metal fibers, etc.

A control module 60 is functional with the engine 12 and the exhaust treatment system 10 connected and monitored by a number of sensors. The control module 60 is also functional with the electric heater 32 the EHC device 22 , the engine 12 and the pressurized vessel 40 connected. An engine-off condition occurs when the pistons 16 in the respective cylinders of the engine 12 are generally stationary. In the embodiment, as shown, is the control module 60 in communication with an ignition switch 70 , The ignition switch 70 sends a signal to the control module 60 indicating the engine off state. Specifically, the ignition switch points 70 a key-on state and a key-off state, wherein the key-off state coincides with the engine-off state. In the key-on state, electric power is supplied to a propulsion system of a vehicle (in FIG 1 Not shown). In the key-off state, no electrical power is supplied to the propulsion system. It should be noted that while the terms "key-on" and "key-off" are used, in some embodiments, no key may be associated with the ignition switch 70 must be used. For example, in one embodiment, the ignition switch 70 be activated by approaching a key fob (not shown) carried by a user instead of a key. Thus, a key-on condition exists when power is supplied to the propulsion system, and the key-off condition exists when power is not supplied to the propulsion system, regardless of whether an actual key is used. It should also be noted that while an ignition switch 70 As well as other approaches may be used to determine the engine-off state.

1 shows the control module 60 in communication with two temperature sensors 62 and 64 that are in the exhaust pipe 14 are arranged. The first temperature sensor 62 is upstream of the SCR device 26 provided, and the second temperature sensor 64 is downstream of the SCR device 26 arranged. The temperature sensors 62 and 64 send electrical signals to the control module 50 , respectively, the temperature in the exhaust pipe 14 specify in specific places.

The control module 60 has a control logic for monitoring the first temperature sensor 62 and the second temperature sensor 64 and calculating a temperature profile of the SCR device 26 on. More precisely, the first temperature sensor 62 and the second temperature sensor 64 averaged together to the temperature profile of the SCR device 26 to create. The control module 60 has a control logic for determining whether the SCR device 26 is below a threshold temperature. The threshold temperature is below a light-off or minimum operating temperature of the SCR device 26 (ie, in one embodiment, the light-off temperature is about 200 ° C). More specifically, the threshold temperature is a predetermined amount below the light-off temperature of the SCR device 26 , This means the SCR device 26 has been cooled to the threshold temperature, allowing the ammonia gas to the SCR device 26 can be stored. In one example, the threshold temperature is in the range between 100 ° C to about 150 ° C, however, it should be understood that the threshold temperature may have other areas as well.

The control module 60 also has control logic for determining if the SCR device 26 has the target amount of ammonia gas charged therein. More specifically, in one embodiment, the control module 60 a control logic for determining whether the engine 12 in the engine-off state, in which the signal from the ignition switch 70 Will be received. In the event that the engine 12 is in the engine-off state, then indicates the control module 60 a control logic for determining if the temperature profile of the SCR device 26 is below the threshold temperature. This means the control module 60 has a control logic for determining whether the SCR device 26 cooled to the threshold temperature, allowing ammonia gas to the SCR device 26 can be stored when the engine 12 is in the engine off state. In the event that the SCR device 26 is below the threshold temperature, then assigns the control module 60 Also, a control logic for determining the amount of ammonia gas in the exhaust pipe 14 through the pressurized vessel 40 has been released.

In the case that the control module 60 determines that the SCR device 26 the target amount of ammonia gas has charged therein, then the control module 60 a control logic for deactivating the pressurized vessel 40 on. Specifically, the control module points 60 a control logic to disable the flash heater 48 which, in turn, causes the decomposition of the solid gas generating material 42 finished in the ammonia gas and carbon dioxide. This in turn disables the metering or injection of the ammonia gas into the exhaust line 14 , In the case that the control module 60 determines that the SCR device 26 the target amount of ammonia gas has not loaded therein, the control module 60 a control logic on to continue the state in which the flash heating 48 of the pressurized vessel 40 is kept activated to generate the ammonia gas.

The control module 60 has a control logic for monitoring the pressure transducer 54 on. The pressure transducer 54 monitors the pressure of the room 50 in the pressure vessel 40 is arranged. The space 50 finally reaches the threshold pressure when the solid gas generating material 42 decomposed into the ammonia gas. Once the control module 60 determines that the threshold pressure has been reached, the normally closed solenoid valve 56 open. The ammonia gas and the carbon dioxide are then in the exhaust pipe 14 released.

The control module 60 also has control logic for selectively enabling or disabling the EHC device 22 based on the temperature profile of the SCR device 26 on. Specifically, when the temperature profile of the SCR device 26 above the light-off temperature, then the electric heater 32 disables and heats the EHC device 22 no more. However, as long as the temperature profile of the SCR device is 22 below the light-off temperature, the electric heater 32 it activates or stays on and heat is sent to the SCR device 26 delivered.

The control module 60 also has control logic for monitoring the temperature of the EHC device 22 on. More precisely, the control module 60 the temperature of the EHC device 22 monitor by several different approaches. In one approach, a temperature sensor (not shown) is downstream of the EHC device 22 placed in communication with the control module 60 for detecting the temperature of the EHC device 22 , In an alternative approach, the temperature sensor is omitted and instead the control module directs 60 a control logic for determining the temperature of the EHC device 22 based on operating parameters of the exhaust system 10 on. More specifically, the temperature of the EHC device 22 based on the exhaust flow of the engine 12 , an input gas temperature of the engine 12 and the electrical power to be charged to the electric heater 32 is delivered. The exhaust gas flow of the engine 12 is by adding the intake air mass of the engine 12 and the fuel mass of the engine 12 calculated, wherein the intake air mass using an intake air mass flow sensor (not shown) of the engine 12 measuring the air mass flow entering the engine 12 entry. The fuel mass flow is calculated by summing the total amount of fuel that enters the engine 12 is released over a given period of time. The fuel mass flow is added to the mass air flow to the exhaust gas flow of the engine 12 to calculate.

The control module 60 has a control logic for determining if the temperature of the EHC device 22 is above a threshold or EHC light-off temperature. In an exemplary embodiment, the EHC light-off temperature is about 250 ° C. If the temperature of the EHC device 22 above the EHC light-off temperature, then the control module points 60 a control logic for de-energizing an electrical source (not shown) of the electric heater 32 on.

The SCR device 26 stores the ammonia gas during the engine off state. This is so because the SCR device 26 has been cooled to the threshold temperature, which is a fixed size below the respective light-off temperature of the SCR device 16 is. Thus, the ammonia gas is not mixed with the SCR Catalyst composition attached to the substrate of the SCR device 26 is arranged before a cold start of the engine 12 react. The SCR device 26 sets a storage of ammonia gas before a cold start of the engine 12 continued. During the engine on state, but before reaching the light-off temperature, the SCR device operates 26 generally as a NO _x adsorber. This means the SCR device 26 is generally capable of NO _x , which is in the exhaust 15 is released when the engine 12 works to adsorb.

The SCR device 26 is during operation of the engine 12 finally heated to the light-off temperature, which is generally the amount of NO _x in the exhaust gas 15 effectively reduced. More specifically, the NO _x in the exhaust gas 15 to nitrogen after the SCR device has started 26 reduced. As discussed above, in one embodiment, the oxidation catalyst compound attached to the EHC device 22 and the OC device 24 is applied, metals such as Pt, Pd or Perovskite. These types of oxidation catalysts can convert NO to NO 2 at a relatively high rate during cold start of an engine compared to some other types of oxidation catalyst compounds currently available. The majority of NO _x , that of the engine 12 is in the form of NO, it being noted, however, that NO 2 is more easily released from the SCR device 26 can be adsorbed as NO. Thus, the conversion of NO to NO 2 at a relatively high rate can reduce NO _x in the exhaust gas 15 through the SCR device 26 support or improve once the SCR device 26 is heated to the light-off temperature.

The EHC device 22 is also downstream of a front 74 the OC device 24 positioned so that hydrocarbons in the exhaust gas 15 the generation of NO to NO2 by the EHC device 22 do not disturb much. In the embodiment, as shown, the EHC device is 22 in the OC device 24 positioned. More specifically, the OC device 24 used in an effort, unburned gaseous and non-volatile HC and CO upstream of the EHC device 22 to treat. Hydrocarbons in the exhaust gas 15 may be the conversion of NO to NO2 by the EHC device 22 to disturb. Thus, the positioning of the OC device supports 24 or a portion thereof upstream of the EHC device 22 a reduction in the amount of NO _x in the exhaust gas 15 By reducing or substantially eliminating hydrocarbons that interfere with NO2 production.

Moreover, the hydrocarbon adsorber 20 configured to reduce the amount of HC that the EHC device has 22 and the OC device 24 during a cold start, which also reduces NO _x in the exhaust gas 15 supported or improved. The hydrocarbon adsorber 20 acts as a mechanism to store fuel or hydrocarbons during a cold start. This means that the hydrocarbons are from the hydrocarbon adsorber 20 before reaching the EHC device 22 and the OC device 24 adsorbed. Thus, the hydrocarbon adsorber 20 also a reduction of the amount of NO _x in the exhaust gas 15 by reducing or substantially eliminating hydrocarbons that interfere with NO2 production.

Now, a method of operating the exhaust treatment system 10 explained. Referring to 2 FIG. 10 is an exemplary process flowchart illustrating an example process for operating the exhaust treatment system. FIG 10 illustrated, generally with reference numerals 200 shown. The process 200 starts at step 202 in which the control module 60 a control logic for monitoring the engine 12 with respect to an engine off state. More specifically, referring to 1 in one embodiment, an engine off condition exists when the pistons 16 generally stationary in the respective cylinders. In an exemplary embodiment, there is an ignition switch 70 in communication with the control module 60 and is used to indicate if the engine on or engine off condition has occurred, however, it should be understood that other approaches may be used to determine the engine off condition as well. If the engine 12 is not in the engine-off state, then the process can 200 end up. The process 200 can in the event that the engine 12 is in an engine-off state, with step 204 Continue.

At step 204 indicates the control module 60 a control logic for monitoring a temperature profile of the SCR device 26 on. More specifically, reference is made 1 the control module 60 in communication with two temperature sensors 62 and 64 that are in the exhaust pipe 14 are arranged, wherein the first temperature sensor 62 upstream of the SCR device 26 is placed and the second temperature sensor 64 downstream of the SCR device 26 is provided. The control module 60 has a control logic for monitoring the first temperature sensor 62 and the second temperature sensor 64 and calculating a temperature profile of the SCR device 26 on. More precisely, the first temperature sensor 62 and the second temperature sensor 64 averaged together to the temperature profile of the SCR device 26 to create. The threshold temperature is below a light-off or minimum operating temperature of the SCR device 26 , More specifically, the threshold temperature is a predetermined amount below the light-off temperature of the SCR device 26 , allowing ammonia gas to the SCR device 26 can be stored. When the SCR device 26 is above the threshold temperature, the process can 200 a monitoring of the temperature profile of the SCR device 26 continue. In the event that the SCR device 26 is below a light-off temperature, the process can 200 then with step 206 Continue.

At step 206 indicates the control module 60 a control logic for determining whether the SCR device 26 loaded a target amount of ammonia gas therein. Specifically, the control module points 60 a control logic for monitoring the amount of ammonia gas flowing into the exhaust pipe 14 through the pressurized vessel 40 has been released, which is the solid gas generating material 42 decomposed into an ammonia gas and carbon dioxide. In the case that the control module 60 determines that the SCR device 26 the process has loaded the target amount of ammonia gas in it 200 with step 208 Continue. At step 208 indicates the control module 60 a control logic for deactivating the pressurized vessel 40 on. Specifically, the control module points 60 a control logic to disable the flash heater 48 on when the flash heater 48 has been activated. A deactivation of the flash heating 48 stops the decomposition of the solid gas generating material 42 into the ammonia gas and carbon dioxide. This in turn disables the metering or injection of the ammonia gas into the exhaust pipe 14 , The process 200 can end then. In the case that the control module 60 determines that the SCR device 26 the target amount of ammonia gas has not loaded in it, the process can 200 then with step 210 Continue.

At step 210 indicates the control module 60 a control logic for monitoring the pressure transducer 54 on. The pressure transducer 54 is used to the pressure of a room 50 in the pressure vessel 40 is arranged to monitor when the room 50 finally reached a threshold pressure. The threshold pressure indicates that the solid gas generating material 42 has been converted to ammonia gas and carbon dioxide at a rate that results in a steady supply of ammonia gas from the SCR device 26 is required. This means the pressure vessel 40 indicates the normally closed solenoid valve 56 which is open in the case that the pressure transducer 52 detects that the pressure in the room 50 has exceeded the threshold pressure. The process 200 can then with step 212 Continue.

At step 212 indicates the control module 60 a control logic for determining if the threshold pressure has been reached. In the event that the threshold pressure has not been reached, the process may 200 to step 210 return where the control module 60 a monitoring of the pressure transducer 54 continues. In the event that the threshold pressure has been reached, the process can 200 then with step 214 Continue. At step 214 becomes a normally closed solenoid valve 56 open. The ammonia gas and carbon dioxide can then enter the exhaust pipe 14 enter. The process 200 can end then.

Although the invention has been described by way of exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention encompass all embodiments falling within the scope of the application.

Claims (10)

An exhaust treatment system for an internal combustion engine, the internal combustion engine having a plurality of pistons and an engine off state indicating that the plurality of pistons are generally stationary, comprising: an exhaust conduit in fluid communication with the internal combustion engine configured during the To receive an exhaust gas from the internal combustion engine; a pressurized vessel storing a solid ammonia gas producing material, the pressurized vessel being selectively activated to heat the solid ammonia gas producing material into an ammonia gas, the ammonia gas being released into the exhaust conduit; a selective catalytic reduction ("SCR") device in fluid communication with the exhaust conduit configured to receive the ammonia gas, the SCR device having an SCR temperature profile and an SCR light-off temperature; a control module in communication with the internal combustion engine and the pressurized vessel, the control module receiving a signal indicative of the engine off condition, the control module having a memory for storing a value indicative of a target amount of ammonia gas entering the exhaust conduit released by the pressurized vessel and charged to the SCR device, the control module comprising: control logic for determining based on the signal whether the engine is in the engine off state; a control logic for determining the SCR temperature profile; control logic for determining if the SCR temperature profile is below a threshold when the engine is in the engine-off state, the threshold indicating that the SCR device is a predetermined amount below the SCR light-off temperature; control logic for determining if the pressurized vessel has released the target amount of ammonia gas into the exhaust passage when the SCR temperature profile is below the threshold; and control logic for deactivating the pressurized vessel when the pressurized vessel has released the target amount of the ammonia gas. The exhaust treatment system of claim 1, wherein the control module includes control logic for monitoring a pressure transducer indicative of pressure internally present in the pressure vessel, and wherein the pressure vessel internally reaches a threshold pressure. The exhaust treatment system of claim 2, wherein the control module includes control logic for activating the pressurized vessel when the threshold pressure is reached and when the pressurized vessel has not released the target amount of ammonia gas into the exhaust passage. The exhaust treatment system of claim 2, wherein the threshold pressure generates the gas spread required to produce gas propagation necessary to produce the target amount of ammonia gas released into the exhaust passage that is charged to the SCR device. The exhaust treatment system of claim 1, wherein the target amount of ammonia gas is an amount necessary to produce a saturation amount of ammonia gas stored by the SCR device, and wherein the saturation amount represents a maximum amount of ammonia gas that the SCR Device can save. The exhaust treatment system of claim 1, further comprising an electrically heated catalyst ("EHC") device in fluid communication with the exhaust conduit configured to receive the exhaust gas during operation of the internal combustion engine and selectively activated to generate heat and oxidation of the exhaust gas, the EHC device having an oxidation catalyst compound disposed thereon for converting nitrogen oxide ("NO") to nitrogen dioxide ("NO ₂ "). The exhaust treatment system of claim 6, further comprising an oxidation catalyst ("OC") device in fluid communication with the exhaust conduit, the OC device having a front surface, the OC device adsorbing and selectively activating hydrocarbons to promote oxidation of the hydrocarbons in the hydrocarbon effect the exhaust gas during operation of the internal combustion engine, wherein the EHC device is positioned in the OC device. The exhaust treatment system of claim 7, wherein at least one of the EHC device and the OC device has an oxidation catalyst compound disposed thereon comprising palladium ("Pd"), platinum ("Pt"), and perovskite. Exhaust treatment system according to claim 7, wherein the control module has a control logic for selectively activating the EHC depending on whether the SCR device has reached the light-off temperature during operation of the internal combustion engine. The exhaust treatment system of claim 1, further comprising an ignition switch, wherein the ignition switch sends the signal to the control module indicative of the engine off condition.

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